Advertisements

I am surprised, that you got only 2.5GB out of your 32bit System. Here it
was 3.1GB, approx. the same amount as with the x64 edition. But I agree, the
memory usage is strange and some folks advised here also, that with x64 I
could use the full 4GB of RAM!

Regards
Dieter

"Martin Racette" <> wrote in message
news:...
> Hi,
>
> I nstalled 4Gb of RAM, using XP Pro 32bit, and Windows is only detecting
> 2.5Gb, I was told that if I installed and use XP Pro x64, I would be able
> to use the whole 4Gb, is this correct ?
>
> --
> Thank you in Advance
>
> Merci a l'Avance
>
> Martin
>
>

Martin Racette wrote:
> Hi,
>
> I nstalled 4Gb of RAM, using XP Pro 32bit, and Windows is only detecting
> 2.5Gb, I was told that if I installed and use XP Pro x64, I would be able
> to use the whole 4Gb, is this correct ?

Can explain to me, in lanment terms, why is that that we loose memory when we
use PCI device, I can not see the relation between the two of them beside the
fact that they are both connect to the motherboard.

--
Thank you in Advance

Merci a l'Avance

Martin

"Charlie Russel - MVP" <> wrote in message
news:...
> Part of the answer to that will depend on the motherboard. You'll lose some
> regardless, since the mobo must support remapping the address space for the
> PCI card BIOSs
>
> --
> Charlie.
> http://msmvps.com/xperts64
>
> Martin Racette wrote:
>> Hi,
>>
>> I nstalled 4Gb of RAM, using XP Pro 32bit, and Windows is only detecting
>> 2.5Gb, I was told that if I installed and use XP Pro x64, I would be able
>> to use the whole 4Gb, is this correct ?
>
>

PCI cards often have BIOSs that control their behaviour. Those BIOSs must
have a memory address (they are a form of memory, just as RAM is) that the
device can use. Since they must work in 32-bit Windows as well as 64-bit
Windows, and 32-bit Windows is limited to 4 GB of directly addressable
memory, they must have an address in that first 4 GB of memory. The area
above 2 GB is used by them, since 32-bit Windows reserves the address space
above 2GB for the operating system to use. (I go into a good deal more
detail about this in several of my whitepapers and columns. See the links
off my blog site.)

Martin Racette wrote:
> Hi,
>
> Can explain to me, in lanment terms, why is that that we loose memory
> when we use PCI device, I can not see the relation between the two of
> them beside the fact that they are both connect to the motherboard.
>
>
>
>
> "Charlie Russel - MVP" <> wrote in message
> news:...
>> Part of the answer to that will depend on the motherboard. You'll lose
>> some regardless, since the mobo must support remapping the address space
>> for the PCI card BIOSs
>>
>> --
>> Charlie.
>> http://msmvps.com/xperts64
>>
>> Martin Racette wrote:
>>> Hi,
>>>
>>> I nstalled 4Gb of RAM, using XP Pro 32bit, and Windows is only detecting
>>> 2.5Gb, I was told that if I installed and use XP Pro x64, I would be
>>> able to use the whole 4Gb, is this correct ?

Martin Racette wrote:
> Can explain to me, in lanment terms, why is that that we loose memory
when we
> use PCI device, I can not see the relation between the two of them
beside the
> fact that they are both connect to the motherboard.

The connection is that PCI can also have memory, such as your graphics
card. It needs to be addressed by the CPU, so it is cutting into the 4GB
of memory that a CPU can address in 32bit mode (without tricks). The
amount of memory space reserved for PCI devices differs, it is usually
something like 512 MB or 1GB.

With a 64bit OS installed, there is no relevant address limit, so you
should be able to use all 4GB (or more). However, as Charlie pointed
out, there are stupid motherboard designs where the memory space using
by PCI bus "hides" the same amount of real memory. In that case you
would only see a significant improvement if you install more memory.

Thank to all for the information, it is a lot clearer now than when I installed
the memory and lost half of it

--
Thank you in Advance

Merci a l'Avance

Martin

"Thomas Steffen" <> wrote in message
news:...
> Martin Racette wrote:
> > Can explain to me, in lanment terms, why is that that we loose memory
> when we
> > use PCI device, I can not see the relation between the two of them
> beside the
> > fact that they are both connect to the motherboard.
>
> The connection is that PCI can also have memory, such as your graphics card.
> It needs to be addressed by the CPU, so it is cutting into the 4GB of memory
> that a CPU can address in 32bit mode (without tricks). The amount of memory
> space reserved for PCI devices differs, it is usually something like 512 MB or
> 1GB.
>
> With a 64bit OS installed, there is no relevant address limit, so you should
> be able to use all 4GB (or more). However, as Charlie pointed out, there are
> stupid motherboard designs where the memory space using by PCI bus "hides" the
> same amount of real memory. In that case you would only see a significant
> improvement if you install more memory.
>
> Thomas

Share This Page

Welcome to Velocity Reviews!

Welcome to the Velocity Reviews, the place to come for the latest tech news and reviews.

Please join our friendly community by clicking the button below - it only takes a few seconds and is totally free. You'll be able to chat with other enthusiasts and get tech help from other members.
Sign up now!